Skin and colouration Ichthyosaur

an ichthyosaur coprolith

typically, fossils preserve suggest skin of ichthyosaurs smooth , elastic, lacking scales. however, these remains not impressions per se, outlines formed bacterial growth. in 1 case, true impression of skin reported specimen of aegirosaurus found in solnhofen plattenkalk, rocks capable of preserving finest detail. minuscule scales seemed visible in specimen.

the colouration of ichthyosaurs difficult determine. in 1956, mary whitear reported finding melanocytes, pigment cells in reddish-brown pigment granules still present, in skin specimen of british fossil, r 509. ichthyosaurs traditionally assumed have employed countershading (dark on top, light @ bottom) sharks, penguins, , other modern animals, serving camouflage during hunting. contradicted in 2014 discovery of melanosomes, black melanin-bearing structures, in skin of ichthyosaur specimen yorym 1993.338 johan lindgren of lund university. concluded ichthyosaurs uniformly dark coloured thermoregulation , camouflage them in deep water while hunting. in contrast mosasaurids , prehistoric leatherback turtles, found countershaded.however, 2015 study doubted lindgren s interpretation. study noted basal layer of melanosomes in skin ubiquitous in reptile coloration, not correspond dark appearance. other chromatophore structures (such iridiophores, xanthophores, , erythrophores) affect coloration in extant reptiles preserved or identified in fossils. thus, due unknown presence of these chromatophores, yorym 1993.338, have been countershaded, green, or various other colors or patterns.